Latest Galileo Satellites Will Head to Plane A

The Soyuz launcher is transferred to the launch pad. (Credit: Arianespace)

I had the honour of the first question at today’s Galileo press conference hosted by the European Space Agency (ESA), and it was about the status of the satellites launched last March. The answer to that question and others are below.

The satellites being launched this evening are destined for Plane A and will be its first occupants. They will occupy slots 5 and 8 in the plane. They will undergo a 76-day-long in-orbit test procedure before being made available to users.

The satellites launched in March, Galileo satellites 7 and 8 (a.k.a. FOC-FM3 or GSAT0203 and FOC-FM4 or GSAT0204 using PRNs 26 and 22, respectively), have essentially completed in-orbit testing and should be available to users sometime this month.

The ground segment is to be modified to enable the production of navigation messages for satellites 5 and 6 (a.k.a. FOC-FM1 or GSAT0201 and FOC-FM2 or GSAT0202 using PRNs 18 and 14, respectively) launched in August 2014 into wrong orbits (a “kind of Plane D” according to one of the ESA officials at the press conference). This will occur by the beginning of 2016 when these satellites will then be available for testing in navigation and positioning applications. They will not be included in the broadcast almanac as the orbits are too far from nominal to be represented by the standard almanac format. But the signals should be fully usable by those receivers and chipsets that can acquire and track Galileo satellites without an almanac. Testing will be carried out to see if the satellites can become part of the operational constellation.

IOV-4 (a.k.a. FM4 or GSAT0104 using PRN 20), the in-orbit validation satellite that suffered a power failure in May 2014 and is only broadcasting on the E1 frequency, may become operational for single-frequency use if suitable ground segment modifications can be made.

The next Galileo launch after this evening’s will be in December on a Soyuz launcher when another two satellites will be placed into orbit.

In 2016, there will be one launch but using, for the first time, the Ariane 5 launcher, to place four satellites into orbit.

In 2017, there will be two launches: a Soyuz launch orbiting two satellites, and an Ariane 5 launch, orbiting four satellites.

A 30-satellite constellation will be in place by 2020, following ESA’s slogan “30 satellites by 2020,” with 10 satellites per plane with each plane having two spare satellites. This should be feasible as two satellites are now being manufactured every three months. Twenty-four satellites is the minimum for Galileo operational capability.